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Hierarchical nanostructures with outstanding electrochemical properties and mechanical stability are ideal for constructing flexible hybrid supercapacitors. Herein, hierarchically hollow NiCo2S4@NiS nanostructures were designed and synthesized by sulfurizing the hierarchical NiCo double hydroxides (DHs) coated with nickel hydroxide nanostructures on carbon fabrics (NiCo-DHs@Ni(OH)2/CF), which trigger excellent electrochemical performances. The NiCo2S4@NiS/CF exhibits a high specific capacity of 1314.0 C g−1 at a current density of 1 A g−1, and maintains the rate performance at about 79.2% of the initial capacity at 30 A g−1. The hybrid supercapacitors of NiCo2S4@NiS//AC display a high energy density of 62.4 W h kg−1 at a power density of 800 W kg−1 with a remarkable cycling stability (96.2% of initial capacitance after 5000 cycles) and robust mechanical flexibility (no obvious decay of specific capacitance during various deformations). Consequently, NiCo2S4@NiS electrodes are expected to be a promising candidate for new smart energy storage devices with high security, stability and flexibility.

High-performance energy storage systems are becoming essential to cope with the possible energy crisis in the future. Herein, unique hierarchical B-Co4N have been reasonably designed and synthesized on Ni foam (NF) via a typical chemical reduction strategy. The successful realization of B-doping engineering effectively facilitates ion and electron transport, adding the electrochemically reactive sites, which endow the B-Co4N-20/NF electrode with high specific capacity (817.9 C g-1 at 1 A g-1), excellent rate capability (maintained about 90.9% at 10 A g-1) and cycling stability (about 93.06% retention of the initial capacity after 5000 cycles). The corresponding hybrid supercapacitor assembled with B-Co4N-20/NF electrodes has an energy density of 25.85 W h kg-1 at the power density of 800.2 W kg-1 and a long cycle life (98.59% retention ratio after 5000 cycles). These remarkable properties indicate that the doping of heteroatom and the construction of hierarchical structure will provide a favorable reference for the performance promotion of next-generation energy storage devices.

ZnCo2S4 nanoneedle clusters are uniformly grown as a core on foamed nickel and then are coated with Ni(OH)2 nanosheets as shell layers. The formed ZnCo2S4@Ni(OH)2 core–shell structures as electrode materials exhibit high specific capacitance (1193 C g−1 at 1 A g−1) and superior cycle rate performance (a capacity retention rate of 92% after 8000 cycles). The ZnCo2S4@Ni(OH)2//AC asymmetric supercapacitor composed of AC//NF as the negative electrode, ZnCo2S4@Ni(OH)2 as the positive electrode, porous glass fiber paper as the separator and 3 mol L−1 KOH as the electrolyte shows a specific capacitance of 215 F g−1 at 1 A g−1 with 70% capacitance retention and 100% coulombic efficiency even after 5000 cycles at a scan rate of 5 A g−1, evidencing the excellent energy storage capacitance and electrochemical performance. Besides, the ZnCo2S4@Ni(OH)2//AC device exhibits an exceptional energy density of ∼44 W h kg−1 at a power density of ∼0.83 kW kg−1.